Effects of amphetamine on brain energy metabolism and protein synthesis are being investigated under conditions which give rise to changes in body temperature in response to the drug. In particular, metabolic changes associated with drug-induced hyperthermia are being correlated with hyperthermia-dependent inhibition of brain protein synthesis by amphetamine. Effects on protein synthesis are determined by means of brain polyribosome profiles. Metabolites of interest include brain glucose, glycogen and high-energy phosphates, especially guanine nucleotides. Methods for the assay of GTP, GDP and GMP have been improved.